Baleen whales were almost hunted to extinction. Now they face a new threat – global shipping. But despite humans blighting their lives, can they now recover and help revive ocean life?Justin Rowlatt speaks to two researchers who observe these intelligent, sociable giants up close. Matt Savoca at Stanford University explains the scale of the slaughter inflicted by whalers in the twentieth century, while Ryan Reisinger of Southampton University describes how modern ships continue to harm whales.By virtue of their sheer enormity, these animals also underpinned entire ocean ecosystems that have since collapsed, as veteran oceanic researcher Victor Smetacek explains. So with their numbers finally recovering, what can we humans do to help? Justin asks Guy Platten, secretary general of the International Chamber of Shipping.Presenter: Justin Rowlatt Producer: Laurence Knight Picture: Aerial view of a whale getting up close to a boat in the Sea of Cortez in the Gulf of California; Credit: Mark Carwardine/Future Publishing/Getty Images